The invention relates to a package for the packaging of solid, liquid or pasty foodstuffs, such as dairy products, delicatessen products and meats, and of medical products.
It will be used in industries for the manufacture of films for food and packages, and for the packaging of foodstuffs subsequently made available to consumers in shops. The use of packages for solid or pasty foodstuffs has long since been known. They consist, of a tray and a cover, also referred to as a seal, made from a thermoformable film suitable for contact with food.
Foodstuffs can be packaged in accordance with the following steps: the roll of plastic film is unwound, then thermoformed in order to produce the tray. The tray is then filled with the foodstuff to be packaged. The cover is then closed over the tray by welding, after the injection of an inert gas in order to preserve the foodstuff.
When the package is opened at the time of consumption of the foodstuff, the weld is broken by the user and the cover is separated from the tray. It is then impossible for the cover to be reclosed over the tray, forcing the user either to consume the product all at once or to use a protective film to preserve the freshness of the product or to prevent the odors from the product spreading within the refrigerator.
It is known in the prior art to produce packages for foodstuffs provided with a device for reclosing the cover over the tray.
The tray is made by thermoforming from a rigid or flexible film of PVC, polyester or a similar plastic.
The cover used on the market today is made from a film consisting of three layers:
an inner weldable layer welded along a bead against the edge of the opening of the tray,
an outer layer which both forms the rigid element of the cover and provides protection against oxygen in order to preserve the food,
an intermediate permanent-adhesive layer.
When the package is used for the first time, the weld bead is detached from the weldable layer and remains integral with the tray. The adhesive layer is then exposed on the cover at the weld bead. This allows the package to be reclosed after its first use and allows the product to be consumed in several portions over several days or several hours.
It has been noted that, when the cover is welded on to the tray, xe2x80x9cpocketsxe2x80x9d are produced on the adhesive layer, these allowing the inert gas for preserving the foodstuff to escape and oxygen to penetrate into the package, thereby oxidizing the foods and reducing their shelf life.
As the adhesive layer is situated in front of the layer providing protection against oxygen, the xe2x80x9cpocketsxe2x80x9d completely destroy the efficiency and properties of the oxygen barrier layer. This therefore means that the solid or pasty foodstuffs become perishable before they are first consumed and that the use-by date of the solid or pasty foodstuffs cannot be specified precisely.
These xe2x80x9cpocketsxe2x80x9d are produced on the package when the cover is welded on to the tray as variations in temperature of the thermoforming machines and in welding pressures are too high or too low.
This invention remedies these disadvantages and one of its main aims is to provide a package for the packaging of foodstuffs, the manufacture of which allows the preservative inert gas to be kept perfectly within the package, thereby allowing for a precise guarantee of the shelf life of the product prior to the first use and therefore prior to the use-by date of the foods.
Another aim of this invention is to enclose the solid or pasty foodstuff within a pouch allowing the packaged product to be preserved in its entirety and without any deterioration of the latter.
Another aim is to eliminate the disadvantages resulting from xe2x80x9cpocketsxe2x80x9d on the adhesive layer allowing the preservative inert gas to escape and oxygen to penetrate into the package, as, in this invention, the xe2x80x9cpocketsxe2x80x9d on the adhesive layer no longer open into the pouch, which thus remains tight and impermeable.
This therefore provides more flexibility when using thermofoming machines, as the variations in temperature and welding pressure are no longer as important or significant and the machines therefore no longer require such strict temperature and pressure control. The aim of this is to simplify the technology used for control and therefore to reduce the cost thereof.
Another aim is to produce the package without any modification of the existing automatic thermoforming machines on the market, the processes for the manufacture of the package and for the packaging of the food product being identical to those existing at present.
Another aim of this invention is to provide a package with simple opening and reclosing of the cover over the tray, thereby dispensing with the need to use protective films to preserve the product when the latter is not consumed completely upon the first use. Reclosing the package also serves to keep the odours from the foodstuff within the package instead of spreading within the refrigerator.
Other aims and advantages of this invention will be clear from the following description given solely by way of a non-limiting example.
Package (1) for the packaging of solid, liquid or pasty foodstuffs, such as dairy products, delicatessen products and meats and for the packaging of medical products, allowing for simple opening and reclosing of a cover over the package, composed of:
a rigid or flexible tray (2) using a thermoformable structure comprising:
an outer supporting layer (5) of amorphous polyester or the like,
an intermediate permanent-adhesive layer (6),
an inner weldable layer (7) of polyethylene,
a cover (3) having a weldable layer of polyethylene, or a thermoformable structure similar to that of the tray (2),
characterised in that the package (1) has an impermeable, tight pouch (8) which receives the foodstuff, defined by:
the weldable layer (7) of the tray (2),
the weldable layer forming the cover (3),
the weld bead (4),
in order to strengthen the hermetic seal of the package (1) and to preserve its tightness until the use-by date of the foodstuff (19) prior to the first opening of the package.